arm compiler has no VFP or NEON in default flags

[ramcq]

It seems that due to https://bugzilla.yoctoproject.org/show_bug.cgi?id=139 and the fact that we use the Yocto "target" GCC instead of the "SDK" GCC, our setting of armv7a-neon (specifically the fact that this tunes the FPU to NEON which also enables VFP3) is not being passed on to the gcc inside the SDK. This caused a build failure in LibreOffice in a place where VFP3 was being assumed, but will across the board cause poor performance on 32-bit ARM systems. Once we've fixed it, we will need to rebuild all of our SDKs and ARM flatpaks. Incidentally changing this should also correctly bubble up the default availability of NEON, which I believe was messing up WebKit builds on ARM.

[ramcq]

#10